Found class constants inside a trait PHP-E1113

One or more class constants have been defined inside a trait. The class constants can only be defined inside a class. Defining class constants outside a class can lead to runtime errors.

It is recommended to extract these class constants inside a standalone class. If you are using PHP 8.1 or later, you can also use Enumeration constants to define these generic constants.

Bad practice

trait StatusTrait
{
    // invalid: a trait can't have constants
    public const DRAFT = 'draft';
    public const PUBLISHED = 'published';
    public const ARCHIVED = 'archived';
}

Recommended

class Status
{
    public const DRAFT = 'draft';
    public const PUBLISHED = 'published';
    public const ARCHIVED = 'archived';
}

Or, use enumeration constants(Only supported in PHP 8.1 and later):

enum Status
{
    public const DRAFT = 'draft';
    public const PUBLISHED = 'published';
    public const ARCHIVED = 'archived';
}

References

• Class Constants
• Traits